Reflector for automobile headlamps



W. F. LITTLE.

REFLECTOR FOR AUTOMOBILE HEADLAMPS.

APPLICATION FILED FEB. 25, 1922.

1 4241 2 1 (8, Patented Aug. 29, 1922.

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. Be it known that'll WILLIAM F. LITTLE, a

' citizen-golf the United tates; residing at Nepnerhanfltleights, county of Westchester, htate of New York (post-ofice address 75'. Grand View Avenue, Ne perhan Heights,

' NewdZ'Or-khhave invente certain new and useful Improvements-in Reflectors for Automobile Headlamps, of which the following is a full, clear, and exact specification.

Tn ap lication for LettersPatent or the United tates, filed February 26-, 1921, Sem1 No. 447,980,1Pat. 1,415,373 May 9, 1922, i

describe certain new and useful improvements in. automobile head lamps in which the light was distributed by a combination of I paraboloidal and hyperboloidal reflectors so! as to secure a concentrated light beam along the axis of the lamp, and oblique homes or hands of general illumination merging with the central beam and extending downwards and outwards therefrom for the purpose of illuminating the sides of the road; and in said application I point out the pract cal value of such light distribution especially for I securing absence of glare in the eyes of an approaching driver, and the efl'ectiveness of illumination both as to the center as well as the sides of the road.

My present invention relates to mprovements by which I am able to secure a l ght distribution having the same advantages, and in which the reflectors used are hyperboloidal only. It is in fact possible to secure any desired type of beam from" an automobile headlamp reflector, by'the use of hyperbolic sections of properly proportioned axes. I

To secure the most concentrated beam the'hyperbolic sections should have a transverse axis very much greater than'the conjugate axis; To secure any de es of spread, axes should be selected accor ingly and the values substituted in the equation of the" hyperbola. Thus a reflector may be constructed of hyperboloidal sections alone which will project any desired combination of concentrated and spread beams as would be reflected from parabolic and hyperbolic sections as de-'- scribed in my said application. The hyperbolic sections may have either coincident axes or convergent or divergent-axes, in order to overlap or separate the beams from each section, to build up the desired beam cross-section.

T will now describe my invention as apaccompan in plied to the formation of abeam havinga central portlon ofhigh candle-power with two arms or bands extending to the right and left, the axes of the latterinclining downward and outward at angles of to degrees to the horizontal, and the arms orv bands being graduated in candle-power from a high value in the center to alower value at the extremities, reference being had to the drawing forming a part of this speci cation and in which:

Fig. 1 is a plan view of my improved reflector composed of six hyperbcloidal sections;

2, a vertical section thereof; and Fig. 3, a diagram illustrating the. beam 'reflected from the sections as the same would appear on a vertical screen.

in the above views, corresponding parts are represented by the same characters.

, The reflector comprises sections 1, 2, 3, 4;, 5. and 6, all of said sections being hyperboloidal. The relative areas of the sections may be varied somewhat, but as a convenient proportioning I make the section 1 to encompass an arc of 60, the section 2 to encompass an arc of 7 0, the sections 3 and t each'encompassing an arc of and the sections 5 and 6 each encompassing an arc of The section 1 at the top or the reflector, has, as an illustration of a proper design, a focal length of one and one-quarter (1%) "inches, with a transverse axis very long as.

compared with the conjugate axis. Such a section will project a highly concentrated beam A, as shown in Fig. 3.

The section 2 at the bottom of the reflector,

may have a focal length clone and one-quarter (1%) inches, with a somewhat shorter transverse axis, thus projecting a beam B of somewhat wider spread, as shown in Fig. 3, and somewhat overlapping the beam A. The two sections 3 and 4, adjacent the section 2, have the same conjugate axes, and shorter transverse axes, the same focal length (one and one-quarter inches), and coincident axes. These two sections project two ellipticalshaped beams G and having portions which, as shown in Fig. 3, over-lap each other and also overlapping the central concentrated beam or at least a portion thereof. The transverse axes are inclined to the horizontal 271, to the right and left. By thus properly proportioning the axes of these sections 3 and 4, I produce ellipses of illumination extending outwardly and downwardly six feet at a distance of one hundred feet from the reflector. I

The remaining sections 5 and 6 are disposed on either side of the section 1, and with the latter comprise the upperhalf of the reflector. B these sections 5 and 6, I project ellipses and F overlapping each other at a portion of their area as well as overlapping the ellipses C and D, and a ortion of the central beam as shown in 3. These ellipses E and F have a transverse axis about fifteen feet lon ata distance of one hundred feet from t e reflector. In

.- order that the ellipses may be projected downwardly and outwardly from the center of the concentrated portion of the beam,

the axes of the sections 5 and 6 must intersect each other. The two planes in which these axes lie pass through the axes of the other hyperbolic sections and the two planes is therefore two small .superimposed sub;

stantially circular patches of light A and B, projected from sections 1 and 2, two elliptical patches of light C and D, the transverse axes being approximately three times the conjugate axes and the transverse axes of these elliptical patches being-disposed downward to the right and left at angles of 27-;

to the horizontal and the two elliptical patches of light El and F, with transverse axis approximately five times the conjugate axes and substantiall similarly disposed.

Having now descri ed my invention, what K claim and desire to secure by Letters Patent is as follows:

1. A reflector for automobile head lamps comprising hyperbolic sections, one of said sectlons projecting a central beam of -hig*h other hyper- -tially as set forth.

' Witnesses:

am e candle-power, and two of said sections projecting oblique bands of light. of less illumination, said bands overlapping each other, merging with a central beam and extending obliquely downward and outward to illuminate the sides of the road, substantially as set forth.

2. reflector for automobile head lamps comprising hyperbolic sections, two of sai sections projecting superimposed beams of high candle-power, and two other sections pro ectm bands of reduced illumination, said ban s over-lapping the centrally superimposed beams and extending downward and outward to illuminate the sides of the road, substantially as set forth.

3. reflector for automobile head lamps, COIIIPI'ISIIIglIYPGIbOliC' sections, one of said. sections pro ecting a concentrated beam of high candle-power, two of said sections proj ecting'bands of reduced illumination mergin with the central beam and extending ob iquely downward and outward, and two other of said sectionsv projecting oblique bands of greater area and less illumination superimposed upon the first mentioned oblique bands, substantially as set forth.

4. A reflector for automobile head lamps, comprising hyperbolic sections, two of said sections pro ecting superimposed concentrated beams of high candle-power, another two of said sections projectin oblique bands of reduced illumination, said bands merging with the central beam and extend-- ing downward and outward, and two further sections projectin oblique bands of greater area but less ifiumination su erimposed upon the first mentioned ban s, substan- This specification signed and witnessed this 31st day of January, 1922.

WILLI r. LITTLE;

NORMAN D. MACDONALD, 4

EDGAR D. Dom. 

